Exam 1 Review Flashcards
6 functions of bone
- Mechanical Support
- Protection
- Facilitates Movement
- Mineral Storage
- Blood Cell Production
- Energy Storage
Cellular Composition of Bone
-30% Organic
-70% Inorganic
Primary Bone Cells
Osteoblast
Osteoclast
Example of inorganic bone compound
Hydroxyapatite
Example of organic bone compound
Collagen
Osteoblast
Bone formation
Osteoclast
Bone reabsorption
Define bone remodeling
Involves the removal of mineralized bone by osteoclasts followed by the formation of bone matrix and mineralization through the activity of osteoblasts.
Phases of bone remodeling
Reabsorption
Reversal
Formation
Reabsorption phase of bone remodeling
Osteoclasts digest old bone
Reversal phase of bone remodeling
mononuclear cells appear on bone surface
Formation phase of bone remodeling
Osteoblasts lay down new bone until the reabsorbed bone is completely replaced.
Wolff’s Law
- Natural healthy bones will adapt and change to adapt to the stress that it subjected to
- “Bone will be laid down where needed
and resorbed where not needed.”
Piezoelectric Effect
Ability of certain materials to generate an electric charge in response to applied mechanical stress
Phases of Piezoelectric facilitated bone remodeling
- Mechanical load causes slippage of collagen fibers
- Fiber slippage results in a movement of ions across the bone surface
- Ion movement produces an electrical potential across the bone
- Shift in electrical potential attracts osteoblasts
- Osteoblasts begin to deposit minerals (primarily calcium)
- Formation of new bone tissue
What is the primary takeaway of the Piezoelectric effect in terms of bone remodeling?
External forces induce an electrical charge which may lead to bone healing and repair
How is bone stress influenced by muscle activity?
Muscles create movement by exerting their forces on bone, this can create tensile and compressive forces in the bones with which they interact.
Example of bone compressive forces
Ski boot
- Tricep surae (gastroc and soleus) exert compressive forces on the posterior aspect of the shank, neutralizing the high tensile forces applied to it.
ligament
bone to bone connections
extension of joint capsule
Nearly parallel fibers, some creases
Contain neural receptors
Tendon
Muscle to bone connection
(wide version =aponeuroses)
Parallel fibers
Contains neural receptors
Types of mechanoreceptors found in tendon and ligament
- Ruffini Corpuscles
- Pacinian Corpuscles
- Golgi tendon organs
- Free nerve endings
Ruffini Corpuscles
(endings)
Found mostly in dermis
detect low frequency vibration and pressure
Pacinian Corpuscles
Subcutaneous tissue and mesenteries
detect Vibration and Deep Pressure
Proprioception
Golgi tendon organs
Located in tendon adjacent to myotendinous junction
sense changes muscle tension
Free nerve endings
Dermis and all connective tissue
Pain signals
Sends signal to sensory neurons
Muscle Spindles
Found in skeletal muscle
Changes in muscle length and rate of lengthening
Stress
The force applied per unit area of tissue, where area is measured in the plane that is perpendicular to the force.
Normalized load, force/area
Strain
Indicates the change in length of the tissue from its relative initial length
Normalized deformation
Tendon and ligament key differences
Tendon fibers are parallel
Ligament fibers are nearly parallel but contain some creases, this accounts for toe region
Creep Response
Change in the restling length of a tissue due to stress maintained over a period of time
When stress is maintained, deformation gradually increases
Why does creep occur?
New equilibrium state,
fluid redistribution through tissue
Protein redistribution through tissue
Fluid exudation
Stress Relaxation Response
decrease in tensile stress over tiem that occurs whena body under tensile stress is held at a fixed length.
Why does stress relaxation response occur?
Constant load applied
Fluid exudation,
relaxation because of redistribution of fluids
Describe how the cross sectional area of muscle influences force production
Properties of muscle
- irritability
- Conductivity
- Contractility
- Adaptability
- Extensability
- Elasticity
Components of Hill Model of Muscle
- CE - Contractile Element
- PEE - Parallel Element
- SEE - Series Elastic Element
CE (Hill Model)
Contractile Element: Force Generating Component,
Actin
Myosin
SEE (Hill Model)
Series Elastic Component: Passive and Active elastic elements
Tendons, aponeuroses and other connective tissue - cross bridges may also contribute
Spring that stores and releases energy
PE (Hill Model)
Parallel Elastic Component: Elastic properties of the connective tissues and membranes
Sarcolemma, Sarcoplasmic Reticulum Epi. Peri. and Endomysium
Considering the force length relationship for skeletal muscle , describe the active curve peak.
The peak of the curve is where the most binding sights are available
The optimal region of overlap where there is enough space to shorten and ample cross bridging opportunities
To the left of the peak there is no room to shorten, to the right of the peak there is no overlap and therefore no available binding sites
Considering the force-length relationship for skeletal muscle, describe the passive curve peak
The passive component of the force length relationship represents the force generated by the muscle when it is stretched or shorted without any active muscle contraction.
Slope represents stiffness
Force increases as muscle is stretched
Decreases as muscle is shortened
Determined by the passive elastic components of muscle
Force- Length Relationship of muscle
describes the amount of force that a muscle can produce is affected by its length
Force- Velocity relationship of muscle
Describes how the amount of force that a muscle can produce is affected by the velocity of muscle shortening or lengthening.
Typically a hyperbolic curve
Inverse in contraction
Explained by sliding filament theory - at low velocities many cross bridges, at high velocities cross bridging opportunity is reduced
Lombard’s Paradox
paradoxical co contraction of muscle antagonist contraction despite inhibition of primary mover. E.G. quadriceps and hamstrings simultaneously contracting when rising from a seated position.
Short range muscle stiffness
Resistance to lengthening is greatest in the first few miliseconds of lengthening, this effect tapers as continual force is applied
Function: stabilizes joint in movements that require a fast change of direction.
Four primary mechanisms of the stretch-shortening cycle
- Time to develop force
- Stored elastic energy
- Force potentiation (boosting of cross bridge opportunities)
- Stretch Reflex
